Twitter plugs black-box website vuln

Twitter's security team said it has fixed a serious vulnerability on the site that created micro-blogging mayhem on Tuesday.

The cross-site scripting flaw on the Twitter.com site creates a means for posting code into updates that activated when users rolled their mouse over a link. Moving a mouse over redacted (blacked out) tweets was especially dangerous.

Thousands of people were caught out by the vulnerability, including the former prime minister's wife, Sarah Brown. The bug was largely used for mischief but there were reports of porn and shock site redirects, along with profile corruption and various other unpleasant side effects.

Security watchers warned the flaw might easily be harnessed in phishing attacks so it's just as well Twitter's security team in California roused themselves from sleep to plug the flaw, around two hours after it first appeared.

The XSS attack should now be fully patched and no longer exploitable. Thanks, those reporting it.

Users were able to shield themselves from affected tweets in TweetDeck by filtering out Tweets bearing the phrase "onmouseover=". A video of the effects of the vulnerability, and the worm it spawned, can be found from F-Secure here. ®